Current Search: Carbon (x)
Pages
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Title
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The determination of total organic carbon in seawater.
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Creator
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Peterson, Gary N., Montgomery, John R.
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Date Issued
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1981-01
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PURL
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http://purl.flvc.org/fcla/dt/3358748
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Subject Headings
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Water--Carbon content--Measurement, Seawater--Organic compound content, Plankton
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Format
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Document (PDF)
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Title
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The effects of nitric acid and silane surface treatments on carbon fibers and carbon/vinyl ester composites before and after seawater exposure.
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Creator
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Langston, Tye A., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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This research focuses on carbon fiber treatment by nitric acid and 3- (trimethoxysilyl)propyl methacrylate silane, and how this affects carbon/vinyl ester composites. These composites offer great benefits, but it is difficult to bond the fiber and matrix together, and without a strong interfacial bond, composites fall short of their potential. Silanes work well with glass fiber, but do not bond directly to carbon fiber because its surface is not reactive to liquid silanes. Oxidizing surface...
Show moreThis research focuses on carbon fiber treatment by nitric acid and 3- (trimethoxysilyl)propyl methacrylate silane, and how this affects carbon/vinyl ester composites. These composites offer great benefits, but it is difficult to bond the fiber and matrix together, and without a strong interfacial bond, composites fall short of their potential. Silanes work well with glass fiber, but do not bond directly to carbon fiber because its surface is not reactive to liquid silanes. Oxidizing surface treatments are often prescribed for improved wetting and bonding to carbon, but good results are not always achieved. Furthermore, there is the unanswered question of environmental durability. This research aimed to form a better understanding of oxidizing carbon fiber treatments, determine if silanes can be bonded to oxidized surfaces, and how these treatments affect composite strength and durability before and after seawater exposure. Nitric acid treatments on carbon fibers were found to improve their tensile strength to a constant level by smoothing surface defects and chemically modifying their surfaces by increasing carbonyl and carboxylic acid concentrations. Increasing these surface group concentrations raises fiber polar energy and causes them to cohere. This impedes wetting, resulting in poor quality, high void content composites, even though there appeared to be improved adhesion between the fibers and matrix. Silane was found to bond to the oxidized carbon fiber surfaces, as evidenced by changes in both fiber and composite properties. The fibers exhibited low polarity and cohesion, while the composites displayed excellent resin wetting, low void content, and low seawater weight gain and swelling. On the contrary, the oxidized fibers that were not treated with silane exhibited high polarity and fiber cohesion., Their composites displayed poor wetting, high void content, high seawater weight gain, and low swelling. Both fiber treatment types resulted in great improvements in dry transverse tensile strength over the untreated fibers, but the oxidized fiber composites lost strength as the acid treatment time was extended, due to poor wetting. The acid/silane treated composites lost some transverse tensile strength after seawater exposure, but the nitric acid oxidized fiber composites appeared to be more seawater durable.
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Date Issued
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2008
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PURL
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http://purl.flvc.org/FAU/172669
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Subject Headings
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Silane compounds, Testing, Surface chemistry, Composite materials, Biodegradation, Carbon compounds, Testing
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Format
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Document (PDF)
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Title
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A study of the effects of nanoparticle modification on the thermal, mechanical and hygrothermal performance of carbon/vinyl ester compounds.
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Creator
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Powell, Felicia M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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Enhancement of mechanical, thermal and hygrothermal properties of carbon fiber/vinyl ester (CFVE) composites through nanoparticle reinforcement has been investigated. CFVE composites are becoming more and more attractive for marine applications due to two reasons : high specific strength and modulus of carbon fiber and low vulnerability of vinyl ester resin to sea water. However, the problem with this composite system is that the fiber matrix (F/M) interface is inherently weak. This leads to...
Show moreEnhancement of mechanical, thermal and hygrothermal properties of carbon fiber/vinyl ester (CFVE) composites through nanoparticle reinforcement has been investigated. CFVE composites are becoming more and more attractive for marine applications due to two reasons : high specific strength and modulus of carbon fiber and low vulnerability of vinyl ester resin to sea water. However, the problem with this composite system is that the fiber matrix (F/M) interface is inherently weak. This leads to poor mechanical properties and fast ingress of water at the interface further deteriorating the properties. This investigation attempts to address these deficiencies by inclusion of nanoparticles in CFVE composites. Three routes of nanoparticle reinforcement have been considered : nanoparticle coating of the carbon fiber, dispersion of nanoparticles in the vinyl ester matrix, and nanoparticle modification of both the fiber and the matrix. Flexural, short beam shear and tensile testing was conducted after exposure to dry and wet environments. Differential scanning calorimetry and dynamic mechanical analysis were conducted as well. Mechanical and thermal tests show that single inclusion of nanoparticles on the fiber or in the matrix increases carbon/vinyl ester composite properties by 11-35%. However, when both fiber and matrix were modified with nanoparticles, there was a loss of properties.
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Date Issued
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2012
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PURL
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http://purl.flvc.org/FAU/3352286
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Subject Headings
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Composite materials, Mechanical properties, Nanostructured materials, Testing, Carbon compounds, Testing, Fibrous composites, Testing, Surface chemistry
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Format
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Document (PDF)
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Title
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Investigating biogenic gas dynamics from peat soils of the Everglades using hydrogeophysical methods.
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Creator
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Wright, William J., Comas, Xavier, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Geosciences
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Abstract/Description
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Peat soils are known to be a significant emitter of atmospheric greenhouse gasses. However, the spatial and temporal variability in production and release of greenhouse gases (such as methane) in peat soils remains uncertain, particularly for low-latitude peatlands like the Florida Everglades, as the majority of studies on gas dynamics in peatlands focus on northern peatlands. The purpose of the work outlined here is focused on understanding the spatial and temporal variability in biogenic...
Show morePeat soils are known to be a significant emitter of atmospheric greenhouse gasses. However, the spatial and temporal variability in production and release of greenhouse gases (such as methane) in peat soils remains uncertain, particularly for low-latitude peatlands like the Florida Everglades, as the majority of studies on gas dynamics in peatlands focus on northern peatlands. The purpose of the work outlined here is focused on understanding the spatial and temporal variability in biogenic gas dynamics (i.e. production and release of methane and carbon dioxide) by implementing various experiments in the Florida Everglades at different scales of measurement, using noninvasive hydrogeophysical methods. Non-invasive methods include ground-penetrating radar (GPR), gas traps, time-lapse cameras, and hydrostatic pressure head measurements, that were constrained with direct measurements on soil cores like porosity, and gas composition using gas chromatography. By utilizing the measurements of in-situ gas volumes, we are able to estimate gas production using a mass balance approach, explore spatial and temporal variabilities of gas dynamics, and better constrain gas ebullition models. A better understanding of the spatial and temporal variability in gas production and release in peat soils from the Everglades has implications regarding the role of subtropical wetlands in the global carbon cycle, and can help providing better production and flux estimates to help global climate researchers improve their predictions and models for climate change.
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Date Issued
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2018
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PURL
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http://purl.flvc.org/fau/fd/FA00013146
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Subject Headings
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Peat soils, Gas dynamics, Carbon cycle (Biogeochemistry), Everglades (Fla), Biogenic gas
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Format
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Document (PDF)
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Title
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THE EFFECTS OF WILLOW SHRUB ENCROACHMENT ON SOIL ORGANIC CARBON STORAGE IN A SOUTH FLORIDA HERBACEOUS WETLAND.
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Creator
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Dell, Jessica Ann, Benscoter, Brian, Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
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Abstract/Description
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Storing almost a third of the global soil carbon pool, wetlands are an essential component of the carbon cycle, and carbon-rich peat soil accumulates when carbon input through primary productivity exceeds output through decomposition. However, woody shrub encroachment in herbaceous wetlands can alter soil carbon processes, potentially diminishing stored carbon. To examine the effects of shrub encroachment on soil carbon, I compared soil carbon input through litterfall and fine root production...
Show moreStoring almost a third of the global soil carbon pool, wetlands are an essential component of the carbon cycle, and carbon-rich peat soil accumulates when carbon input through primary productivity exceeds output through decomposition. However, woody shrub encroachment in herbaceous wetlands can alter soil carbon processes, potentially diminishing stored carbon. To examine the effects of shrub encroachment on soil carbon, I compared soil carbon input through litterfall and fine root production, output through decomposition, and below-canopy microclimate conditions between Carolina willow shrub (Salix caroliniana) and herbaceous sawgrass (Cladium jamaicense) in the Blue Cypress Marsh Conservation Area (BCMCA), FL. To assess the level of production and its response to water level, I compared aboveground green biomass by measuring normalized difference vegetation index (NDVI) and photosynthetic stress by measuring photochemical reflectance index (PRI) between sawgrass and willow. I collected willow litterfall using litter traps and measured sawgrass and willow fine root production with fine root ingrowth bags. Litter decomposition was measured with decomposition bags deployed using a reciprocal litter placement design at BCMCA and incubated in a greenhouse to examine the effects of char and water level on decomposition. Above and belowground microclimate conditions were measured using sensors installed within sawgrass and willow canopies. Despite experiencing more photosynthetic stress, willow produced more green biomass than sawgrass. However, willow produced fewer fine roots than sawgrass and these roots were deeper within the soil. Willow litter decomposed faster even though sawgrass decomposition increased under drier conditions. Compared to the sawgrass canopy, the willow canopy had greater light availability, lower evaporative demand plus warmer and drier soils; however, litter decomposition did not differ between the canopies. These results suggest that willow encroachment can reduce the amount and alter the distribution of carbon within an herbaceous wetland, likely resulting in a net loss of soil carbon. Although willow encroachment may increase aboveground biomass carbon stocks, these stocks will likely be offset by a loss of soil carbon due to reduced fine root production and increased decomposition. Therefore, the transition from herbaceous wetland to shrub wetland will likely result in a loss of stored soil carbon.
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Date Issued
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2020
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PURL
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http://purl.flvc.org/fau/fd/FA00013621
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Subject Headings
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Wetlands, Blue Cypress Water Management Area (Fla), Carbon cycle (Biogeochemistry), Soils
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Format
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Document (PDF)
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Title
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Chemical Method and Device to Detect Underwater Trace Explosives via Photo-Luminescence.
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Creator
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Langston, Tye A., Florida Atlantic University, Granata, Richard D., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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This research tests the use of sensitized lanthanide ions to determine if they can detect water-borne explosive traces and produces two designs for a field-deployable underwater explosive trace detector. 1,1 0-phenanthroline and thenoyltritluoroacetone are evaluated as sensitizing ligands to absorb energy and initiate the fluorescence process in europium ions. Different compounds obtained via ligand choice and mixing order are evaluated for their ability to produce a large fluorescence...
Show moreThis research tests the use of sensitized lanthanide ions to determine if they can detect water-borne explosive traces and produces two designs for a field-deployable underwater explosive trace detector. 1,1 0-phenanthroline and thenoyltritluoroacetone are evaluated as sensitizing ligands to absorb energy and initiate the fluorescence process in europium ions. Different compounds obtained via ligand choice and mixing order are evaluated for their ability to produce a large fluorescence differential between explosive-laden and explosive-absent solutions. Optimal excitation and emission wavelengths for several different compounds are determined, as well as practical wavelengths to be applied in the field. The effect of methanol as a solvent to deliver the reagents is evaluated and rough solubility limits are determined. The effects of seawater constituents on detection are investigated and explosive detection limits are determined. It was found that this method and device are viable for underwater explosive trace detection. A field-deployable device is designed, characterized, and proven.
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Date Issued
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2006
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PURL
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http://purl.flvc.org/fau/fd/FA00012600
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Subject Headings
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Silane compounds--Testing, Surface chemistry, Composite materials--Biodegradation, Carbon compounds--Testing
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Format
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Document (PDF)
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Title
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Effects of POSS Fiber Sizing on the Mechanical and Thermal Properties of CarbonNinyl Ester Composites.
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Creator
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Powell, Felicia M., Mahfuz, Hassan, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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The degradation of polymer composites in moist environments is a limiting factor in the advancement of composite technology. The key to mitigate this degradation is to maintain the integrity of the fiber/matrix (F/M) interface. In this study, the F/M interface of carbon/vinyl ester composites has been modified by treating the carbon fiber with polyhedral oligomeric silsesquioxane (POSS). Two POSS systems, namely octaisobutyl and trisilanolphenyl, have been investigated. A set of chemical and...
Show moreThe degradation of polymer composites in moist environments is a limiting factor in the advancement of composite technology. The key to mitigate this degradation is to maintain the integrity of the fiber/matrix (F/M) interface. In this study, the F/M interface of carbon/vinyl ester composites has been modified by treating the carbon fiber with polyhedral oligomeric silsesquioxane (POSS). Two POSS systems, namely octaisobutyl and trisilanolphenyl, have been investigated. A set of chemical and mechanical procedures has been developed to coat carbon fibers with POSS, and fabricate layered composites using vinyl ester resin. lnterlaminar shear, transverse tension, and low velocity impact tests on composites have indicated around 10-38% improvement in mechanical properties with respect to control samples. Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) tests have also shown significant improvement in glass transition temperature (T9). Hygrothermal tests, under various environments, have demonstrated that POSS reduces water absorption by 20-30%.
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Date Issued
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2009
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PURL
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http://purl.flvc.org/fau/fd/FA00012540
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Subject Headings
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Surface chemistry, Composite materials--Biodegradation, Carbon compounds--Testing, Thermodynamics, Fibrous compounds--Testing
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Format
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Document (PDF)
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Title
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Analysis of modern carbonate sediments: Lubber's Bank, Abaco, Bahamas.
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Creator
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Banks, Kenneth W., Florida Atlantic University, Finkl, Charles W.
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Abstract/Description
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The Bahamas archipelago is comprised of numerous carbonate platforms. Within these platforms are a variety of carbonate depositional environments, each unique and warranting detailed investigations of the interrelationships of physical conditions and trends in sediment texture and composition. This study examines one of these environments, Lubber's Bank. The bank is mapped and the physical hydrographic setting in the vicinity of the bank is examined through field measurements, analysis of...
Show moreThe Bahamas archipelago is comprised of numerous carbonate platforms. Within these platforms are a variety of carbonate depositional environments, each unique and warranting detailed investigations of the interrelationships of physical conditions and trends in sediment texture and composition. This study examines one of these environments, Lubber's Bank. The bank is mapped and the physical hydrographic setting in the vicinity of the bank is examined through field measurements, analysis of satellite pictures and predictive techniques. This information is correlated with analysis of sediment texture and composition. Results indicate that the surface sediments on the bank probably originate in the surrounding sea grass beds and on the bank as skeletal material and may have originated by the accumulation of sediments on antecedent topographic highs during the Holocene transgression.
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Date Issued
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1999
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PURL
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http://purl.flvc.org/fcla/dt/15645
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Subject Headings
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Carbonate rocks--Bahamas, Sedimentation and deposition--Bahamas, Geology--Bahamas
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Format
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Document (PDF)
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Title
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Feasibility studies on carbon fiber composite cables in reinforced/prestressed concrete structures.
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Creator
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Kanneganti, Srikanth., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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The feasibility studies on the use of non-metallic continuous fiber reinforcement in reinforced and prestressed concrete structures are presented herein. Experimental results from studies on relaxation, bond and transfer length of Carbon Fiber Composite Cables (CFCC) are presented followed by results of flexural load tests on concrete beams reinforced and prestressed with CFCC. Durability of the CFCC is another prime concern, and hence part of the study also focuses on establishing the...
Show moreThe feasibility studies on the use of non-metallic continuous fiber reinforcement in reinforced and prestressed concrete structures are presented herein. Experimental results from studies on relaxation, bond and transfer length of Carbon Fiber Composite Cables (CFCC) are presented followed by results of flexural load tests on concrete beams reinforced and prestressed with CFCC. Durability of the CFCC is another prime concern, and hence part of the study also focuses on establishing the durability of the CFCC exposed to aggressive environments like alkali solution and sea water. The basic mechanics that govern the structural behavior of the beams, provide important insight into the potential that CFCC has to offer.
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Date Issued
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1994
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PURL
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http://purl.flvc.org/fcla/dt/15080
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Subject Headings
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Fiber reinforced plastics, Reinforced concrete, Fiber, Composite materials, Prestressed concrete construction--Deterioration, Carbon fibers
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Format
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Document (PDF)
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Title
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Peel-off characteristics of carbon fiber laminates bonded to concrete.
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Creator
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Barbosa, Mauro., Florida Atlantic University, Arockiasamy, Madasamy
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Abstract/Description
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This study presents the experimental and theoretical studies on debond of carbon fiber laminates bonded to concrete, which aids in understanding the mechanics of the repaired damaged prestressed concrete girders with externally bonded carbon plates. The bond strength of carbon plate specimens bonded to concrete is determined experimentally by the debond test. The initial crack is introduced in the specimens at one location, namely the plate/adhesive interface. The fracture toughness for...
Show moreThis study presents the experimental and theoretical studies on debond of carbon fiber laminates bonded to concrete, which aids in understanding the mechanics of the repaired damaged prestressed concrete girders with externally bonded carbon plates. The bond strength of carbon plate specimens bonded to concrete is determined experimentally by the debond test. The initial crack is introduced in the specimens at one location, namely the plate/adhesive interface. The fracture toughness for debonding is evaluated and expressed as the critical strain energy release rate. A finite element analysis was performed to evaluate the compliance and stress distribution in the debond test specimens.
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Date Issued
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2000
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PURL
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http://purl.flvc.org/fcla/dt/12669
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Subject Headings
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Prestressed concrete construction--Maintenance and repair, Fracture mechanics, Carbon composites
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Format
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Document (PDF)
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Title
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Investigation of carbon dioxide transport in life support helmets.
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Creator
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Camperman, John Michael., Florida Atlantic University, Tennant, Jeffrey S., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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This research explores carbon dioxide transport in life support helmet annular space using new theoretical and experimental techniques. Increased transport from next generation helmets is necessary to allow reduction of fresh gas flow and associated noise. Conventional helmet noise interferes with communications and some underwater helmets even approach hearing threshold shift levels. Helmet flow is three dimensional, unsteady, and turbulent; this research is the first known effort to...
Show moreThis research explores carbon dioxide transport in life support helmet annular space using new theoretical and experimental techniques. Increased transport from next generation helmets is necessary to allow reduction of fresh gas flow and associated noise. Conventional helmet noise interferes with communications and some underwater helmets even approach hearing threshold shift levels. Helmet flow is three dimensional, unsteady, and turbulent; this research is the first known effort to identify the fundamental mechanisms of CO2 transport. An analytical model is developed which predicts average inhaled CO2 concentration for generic helmet geometry using a mixing volume approach. The model includes sensitivity to supply flow, breath rate, metabolic CO2 production, inhalation and exhalation mixing volumes, and breathing symmetry. Numerical sensitivity analysis using the model indicates optimum design paths. Nominal head-helmet-lung geometry is identified. An experimental nominal model was developed which supports inhaled concentration measurements with air-CO2 or water-dye as working fluids. Water modeling provides flow visualization which is used to identify complex convective and turbulent CO2 transport mechanisms. Correlation of water-dye and air-CO2 results indicates conditions when molecular diffusion of CO2 is significant. The research was directed primarily toward diving helmets but is applicable to spacesuit and firefighter helmets, as well as any situation involving mass transport in a periodic mixing chamber. New analytical and experimental models are substantially more accurate than the conventional steady state helmet mixing model, and provide direction for improved helmet design.
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Date Issued
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1995
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PURL
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http://purl.flvc.org/fcla/dt/12432
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Subject Headings
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Deep diving--Equipment and supplies, Deep diving--Physiological aspects, Carbon dioxide, Underwater physiology
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Format
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Document (PDF)
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Title
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Electrochemical impedance spectroscopy to monitor degradation of carbon fiber reinforced polymer composites subjected to simulated ocean environment.
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Creator
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Ahmed, Mohammad Mesbahuddin., Florida Atlantic University, Lipka, Stephen M.
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Abstract/Description
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This research evaluated the applicability of electrochemical impedance spectroscopy (EIS) as a non-destructive technique to predict and characterize the degradation of carbon fiber reinforced polymer (CFRP) composites exposed to aqueous environments at ambient and 6.2 $\pm$ 0.3 MPa. Changes in EIS data were related to water uptake into the composite material as a function of exposure time. Electrochemically induced damage (both anodic and cathodic) were also evaluated using impedance...
Show moreThis research evaluated the applicability of electrochemical impedance spectroscopy (EIS) as a non-destructive technique to predict and characterize the degradation of carbon fiber reinforced polymer (CFRP) composites exposed to aqueous environments at ambient and 6.2 $\pm$ 0.3 MPa. Changes in EIS data were related to water uptake into the composite material as a function of exposure time. Electrochemically induced damage (both anodic and cathodic) were also evaluated using impedance measurements. Three point flexure tests with concurrent EIS measurements were employed to study the effect of stresses on water uptake and mechanical degradation. Visual observation of the extent of damage (i.e., fiber-matrix debonding) was made using scanning electron microscopy (SEM) and correlated with EIS observation.
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Date Issued
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1993
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PURL
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http://purl.flvc.org/fcla/dt/14962
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Subject Headings
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Polymers--Deterioration, Composite materials--Environmental aspects, Carbon fibers, Polymeric composites, Spectrum analysis
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Format
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Document (PDF)
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Title
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CO2 absorption capacity of new and old lithium hydroxide used in underwater life support systems.
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Creator
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Wang, Tsen C., Krivan, J. P., Jr., Harbor Branch Oceanographic Institute
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Date Issued
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1997
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PURL
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http://purl.flvc.org/fau/fd/FA00007131
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Subject Headings
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Carbon dioxide--Absorption and adsorption, Lithium hydroxide, Life Support Systems
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Format
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Document (PDF)
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Title
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Elevated pCO2 effects on the macroalgal genus Halimeda: Potential roles of photophysiology and morphology.
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Creator
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Peach, Katherine, Koch, Marguerite, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
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Abstract/Description
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While ocean acidification (OA) is predicted to inhibit calcification in marine macroalgae, species whose photosynthesis is limited by current dissolved inorganic carbon (DIC) levels may benefit. Furthermore, variations in macroalgal morphology will likely give rise to a range of OA tolerance in calcifying macroalgae. One genus of calcifying macroalgae that has shown varying species’ tolerance to OA is Halimeda, a major carbonate sediment producer on tropical reefs. Species within this genus...
Show moreWhile ocean acidification (OA) is predicted to inhibit calcification in marine macroalgae, species whose photosynthesis is limited by current dissolved inorganic carbon (DIC) levels may benefit. Furthermore, variations in macroalgal morphology will likely give rise to a range of OA tolerance in calcifying macroalgae. One genus of calcifying macroalgae that has shown varying species’ tolerance to OA is Halimeda, a major carbonate sediment producer on tropical reefs. Species within this genus occupy a range of habitats within tropical environments (reefs and lagoons), illustrating their ability to adapt to diverse environmental conditions (e.g. carbonate chemistry, irradiance). To date it is not clear if morphological and photophysiological diversity in Halimeda will translate to different tolerances to OA conditions (elevated pCO2 and lower pH).
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Date Issued
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2016
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PURL
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http://purl.flvc.org/fau/fd/FA00004621
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Subject Headings
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Coral reef ecology., Chemical oceanography., Halimeda., Environmental mapping., Plants--Effect of light on., Plant physiology., Photobiology., Carbon cycle (Biogeochemistry)
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Format
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Document (PDF)
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Title
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Effect of Electronic Water Treatment System on Calcium Carbonate Scaling.
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Creator
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Shaha, Bishow Nath, Meeroff, Daniel E., Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
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Abstract/Description
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Calcium carbonate precipitation and formation of clog particles inside the leachate collection pipe can cause catastrophic failures in landfill operation. This study focuses on quantifying the effectiveness of electronic scale control to reduce the clog formation within the pipe network. A field scale model (40ft × 20ft) was constructed, featuring side-by-side flow of electronically treated and untreated composite leachate. Data obtained in the first phase of this study indicate that...
Show moreCalcium carbonate precipitation and formation of clog particles inside the leachate collection pipe can cause catastrophic failures in landfill operation. This study focuses on quantifying the effectiveness of electronic scale control to reduce the clog formation within the pipe network. A field scale model (40ft × 20ft) was constructed, featuring side-by-side flow of electronically treated and untreated composite leachate. Data obtained in the first phase of this study indicate that electronic scale control system does not have any statistically significant effect on water quality parameters. The second phase of this study identified calcite (CaCO3) to be the predominant phase present in the precipitates using XRD/XRF diffraction pattern analyzed through a search match calculation program (MATCH! Version 3.2.0) which concur with the previous studies. Furthermore, Rietveld refinement using FullProf Suite confirms that there were no differences between the treated and untreated precipitate based on the phases identified in the respective samples.
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Date Issued
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2016
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PURL
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http://purl.flvc.org/fau/fd/FA00004706, http://purl.flvc.org/fau/fd/FA00004706
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Subject Headings
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Calcium carbonate, Engineered barrier systems (Waste disposal), Environmental engineering, Green technology, Incrustations, Materials science, Water -- Hardness, Water quality management
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Format
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Document (PDF)
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Title
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Sediment phosphorus fractionation in calcium carbonate sediments of northeastern Florida Bay.
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Creator
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Benz, Robert E., Jr., Florida Atlantic University, Koch, Marguerite
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Abstract/Description
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Different physiochemical processes control phosphorus storage in subtropical versus temperate estuaries; however, few studies are available on sediment phosphorus storage from the subtropics. In this study, solid-phase phosphorus pools of northeastern Florida Bay's sediments were examined by sequential chemical extractions, separating phosphorus into exchangeable, iron-bound, calcium-bound, and residual organic fractions. Calcium-bound phosphorus was the dominant fraction, accounting for...
Show moreDifferent physiochemical processes control phosphorus storage in subtropical versus temperate estuaries; however, few studies are available on sediment phosphorus storage from the subtropics. In this study, solid-phase phosphorus pools of northeastern Florida Bay's sediments were examined by sequential chemical extractions, separating phosphorus into exchangeable, iron-bound, calcium-bound, and residual organic fractions. Calcium-bound phosphorus was the dominant fraction, accounting for approximately 60% of the total phosphorus and 93% of the inorganic phosphorus. Residual organic phosphorus was the second dominant fraction, accounting for 37% of the total phosphorus. In contrast to calcium-bound and residual organic phosphorus, the concentration of iron-bound phosphorus was low, indicating a limited role of iron in long-term phosphorus storage. The fine-grained carbonate sediments of Florida Bay probably account for the large pool of calcium-bound phosphorus, while the proximity of the mangroves to the northeastern section of the Bay may account for the high residual organic pool of phosphorus.
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Date Issued
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2000
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PURL
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http://purl.flvc.org/fcla/dt/15763
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Subject Headings
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Water--Phosphorus content, Marine sediments--Florida--Florida Bay, Calcium carbonate, Florida Bay (Fla )--Environmental conditions
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Format
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Document (PDF)
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Title
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Feasibility of using carbon fiber reinforced plastic tendons in prestressed concrete Double-Tee bridge system.
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Creator
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Zhuang, Ming., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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One of the major problems the construction industry faces today is corrosion of reinforcing and prestressing steel, which significantly affects the durability of concrete structures. Fiber reinforced plastics (FRPs) are highly regarded as prospective replacement for steel in prestressed concrete structures under corrosive environment. This investigation was conducted to establish the feasibility of using Carbon Fiber Composite (CFC) cables as reinforcing/prestressing elements in concrete...
Show moreOne of the major problems the construction industry faces today is corrosion of reinforcing and prestressing steel, which significantly affects the durability of concrete structures. Fiber reinforced plastics (FRPs) are highly regarded as prospective replacement for steel in prestressed concrete structures under corrosive environment. This investigation was conducted to establish the feasibility of using Carbon Fiber Composite (CFC) cables as reinforcing/prestressing elements in concrete bridge structures. Besides investigating durability of CFC cables and pretensioned concrete beams with CFC cables in adverse environments (alkali and seawater), flexure and shear tests were performed on single Double-Tee beams, together with service load behavior, fatigue strength and ultimate load capacity tests on a half scale model Double-Tee girder bridge system prestressed with CFC cables. Exposure to seawater and alkali environments has no adverse effect on the strength of the CFRP tendons as well as the pretensioned beams with CFRP. Based on the flexural strength tests on Double-Tee beams, the bond between CFRP tendons and concrete is satisfactory. The Double-Tee bridge system exhibited good fatigue resistance and adequate ductility under ultimate load conditions. The ultimate load capacity of the bridge is approximately three times the service load corresponding to two HS20-44 trucks and equals 2.4 times the first crack load. Finite element analyses were carried out to predict elastic deformations and collapse load of the Double-Tee bridge prestressed with CFC cables. Feasibility of using CFC cables in bridge structures is assessed based on the experimental and analytical parameters such as deflections, strains, crack distributions and crack widths.
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Date Issued
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1996
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PURL
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http://purl.flvc.org/fcla/dt/12465
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Subject Headings
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Carbon fibers, Composite construction, Fiber reinforced plastics, Bridges, Iron and steel, Reinforced concrete construction, Prestressed concrete construction
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Format
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Document (PDF)
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Title
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A STUDY OF THE EFFECT OF FLOW PARAMETERS ON THE CATHODIC PROTECTION OF A STEEL PLATE IN NATURAL SEAWATER.
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Creator
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MCCABE, KEVIN MICHAEL., Florida Atlantic University, Smith, Samuel W., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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The influence of hydrodynamic parameters and cathodic polarization on the formation of calcareous deposits on a steel plate in flowing seawater is investigated. Current density variations on the plate are determined for a combination of applied potentials and seawater velocities. Equations are developed to relate the cathodic current density distribution to variations in hydrodynamic and diffusional boundary layer thickness along the plate for laminar and turbulent flow regimes. A comparison...
Show moreThe influence of hydrodynamic parameters and cathodic polarization on the formation of calcareous deposits on a steel plate in flowing seawater is investigated. Current density variations on the plate are determined for a combination of applied potentials and seawater velocities. Equations are developed to relate the cathodic current density distribution to variations in hydrodynamic and diffusional boundary layer thickness along the plate for laminar and turbulent flow regimes. A comparison of experimental current densities on a bare plate to that predicted by theory is examined. Effects of flow on the formation and properties of calcareous deposits are discussed in light of recent developments in marine cathodic protection.
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Date Issued
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1984
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PURL
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http://purl.flvc.org/fcla/dt/14192
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Subject Headings
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Plates, Iron and steel--Cathodic protection, Carbon steel--Corrosion, Plates, Iron and steel--Fluid dynamics, Cathodic protection
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Format
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Document (PDF)
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Title
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Theoretical analysis of reinforced and prestressed concrete bridge members strengthened with CFRP laminates.
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Creator
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Qu, Rong., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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Nonlinear finite element analyses of the reinforced rectangular beams, prestressed solid slab and prestressed voided slab retrofitted with CFRP laminates are carried out using the software ANSYS(version 5.0) on the Sunwork station. The computer analyses are based on the proposed stress-strain relationship considering the effects of tensile stress on both elastic modulus and maximum compressive stress of concrete. Several assumptions are made in predicting the loss of tensile strength due to...
Show moreNonlinear finite element analyses of the reinforced rectangular beams, prestressed solid slab and prestressed voided slab retrofitted with CFRP laminates are carried out using the software ANSYS(version 5.0) on the Sunwork station. The computer analyses are based on the proposed stress-strain relationship considering the effects of tensile stress on both elastic modulus and maximum compressive stress of concrete. Several assumptions are made in predicting the loss of tensile strength due to crack, confinement due to the laminate bonding, tensile strength due to the prestress force, failure pattern due to the concentrated stress adjacent to the loading point and concrete crushing due to large compressive strain. A subroutine is developed using macro commands of ANSYS. In this research, Branson's equation or Ie procedure is assumed in the prediction of deflection of retrofitted concrete members. The modifications needed due to laminate bonding are the cracking moments of inertia (Icr) of the beams or slabs bonded with CFRP laminates, which are included in the analysis.
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Date Issued
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1994
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PURL
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http://purl.flvc.org/fcla/dt/15083
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Subject Headings
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ANSYS (Computer system), Reinforced concrete--Plastic properties, Carbon composites, Fiber reinforced plastics, Bridges--Design and construction, Prestressed concrete construction
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Format
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Document (PDF)
Pages